The present invention relates to a secured switch device having one set of surfaces forming an electrical contact guided by a sliding member and said device further including a spring-arming plate, a control shaft actuating the same spring-like elements for transmitting the movement of the spring-arming plate to the sliding member and thence further to the contact surfaces.
From patent publication FI 93502 is known a switch device in which the control lever is at all times movable in a clear and unambiguous manner from one position into another position and the construction of the device excludes the possibility of allowing the electrical contact surfaces to assume an intermediate position. This arrangement prevents the occurrence of excessively long arcs caused by too slow an opening or closing of the contact surfaces, whereby the switch device is protected from damage due to arcing. The switch device is latched in the open and closed positions by means of both mechanical and spring forces, thus assuring positive latching of the switch device in the desired position. The switch device further includes a mechanical force-separating means that separates the contact surfaces should they happen to be welded together. In the case that contact welding has been so intense as not to permit the contact surfaces to be separated from each other, the control lever of the switch device returns to the xe2x80x9cclosedxe2x80x9d position. Hence, no ambiguity about the switch status can occur.
The function of this kind of switch device is implemented by mounting into the switch housing at least one linearly movable sliding member with contacts thereon adapted to cooperate with the stationary contacts of the switch. To the sliding member is via at least one spring-type member connected a spring-arming plate adapted to move in parallel with the sliding member. The spring-arming plate is constructed so that, during the motion of said spring-arming plate, the spring elements cause the sliding member to move correspondingly. One of the advantages of this construction is that the spring-arming plate controls the switching action in an operator-independent manner and always at a high speed, whereby the electrical contacts close and open rapidly and the duration of arcing is minimized. The actual connection step is thus performed at all times with a constant speed forced by the armed springs independently from rotating speed of the switch control lever. Such a switch cannot be inadvertently operated in an incorrect manner.
While the switch device disclosed in patent publication FI 93502 is highly useful, it cannot be employed universally in all applications inasmuch it lacks a remote control function. Today, there is a wide need for a switch device equipped with a remote-control facility. Such a switch device should desirably have the good manual control and switching properties of the above-described prior-art device complemented with facilities fulfilling the following requirements:
The remote-trip function of the device may not interfere with the manual-control properties of the device meaning that switch devices equipped with a remote-trip facility must be usable in the same fashion as switch devices not equipped with a remote trip option.
The switch device must be remote-controllable, e.g., through actuating by means of a solenoid a lever on the switch housing, from its I (closed) position into a Trip position representing an intermediate mechanical state with an electrically open circuit between the I and O (open) positions of the switch.
The switch device must have an auxiliary contact serving to indicate said Trip status.
The switch construction shall not allow direct control of the switch from its Trip status into position I; however, an attempt to do so may allow the manual control lever to move, while the electrical contact surfaces must remain unmoved.
Rearming of the switch device from its Trip status must take place via a Reset action. If so desired, the O position may also serve as the Reset position.
It is an object of the invention to eliminate the short-comings of the above-described prior art devices and to provide an entirely novel kind of a switch device capable of fulfilling the above-stated requirements.
The goal of the invention is achieved by providing a slot in the sliding member guiding the second set of contact surfaces in the switch and equipping the switch housing or body piece with a latch assembly capable of inhibiting the movement of the sliding member through partially entering into the slot of the sliding member. Additionally, the spring-arming plate is provided with a projection adapted to cover the slot of the sliding member, thus inhibiting the latch assembly from interrupting the movement of the sliding member when the switch is manually thrown between its open and closed positions. The switch device is further provided with a second set of springs serving to store the mechanical energy required to actuate the remote-controlled trip function.
More specifically, the switch device according to the invention is characterized by what is stated in the characterizing part of claim 1.
The invention offers significant benefits: a switch device according to the invention provides reliable, durable and safe operation. Rapid changeover between positions is assured in the switch device by mechanical means and, according to the invention, the switch device can also be tripped in a remote-controlled manner. Manual use of the switch device after remote-controlled tripping requires a mandatory arming (Reset) operation and the liberated position of the operating lever always indicates the real status of the mutual disposition of the switch device contact surfaces. These qualities reduce the risk of misinterpretation of switch device status.
In the following, the invention will be examined with the help of exemplifying embodiments by making reference to the attached drawings, in which:
FIG. 1 shows a switch device concerned in the invention with the remote-controlled trip mechanism according to the invention omitted therefrom;
FIG. 2 shows a latch mechanism for the sliding member of the switch device illustrated in FIG. 1;
FIG. 3 shows in a partially sectional view a remote-controlled trip mechanism according to the invention in position O;
FIG. 4 shows the mechanism illustrated in FIG. 3 in its position O and armed for tripping into position I;
FIG. 5 shows the mechanism illustrated in FIG. 3 in its position Trip;
FIG. 6 shows the mechanism illustrated in FIG. 3 with the sliding member in its position Trip and the control lever turned into position I;
FIG. 7 shows the mechanism illustrated in FIG. 3 in position I; and
FIG. 8 shows the mechanism illustrated in FIG. 3 in position I and armed for tripping into position O.